a) Field of the Invention
The invention relates to the field of production or treatment of semiconductor components or other solid-state components and is directed to a method for nanostructuring of amorphous carbon layers.
The method is advantageously applicable in the production of electronic components in the submicrometer range and in the nanometer range and, in this connection, is suitable particularly for generating nanostructured etch masks whose structure is to be transferred to layers located below them. Further, the method according to the invention can be applied for entering information in amorphous carbon layers for the purpose of storing information.
b) Description of the Related Art
Previously, masks for structure transfer into underlying layers by etching or for application of the lift-off method were produced by photolithography and with electron beam lithography. Further, various possibilities are known for generating structures with structure sizes in the nanometer range by scanning probe microscopes. For example, electron beam sensitive lacquers or resists can be exposed by scanning tunneling microscopes (E. A. Dobisz and C. R. K. Marrian, Appl. Phys. Lett. 58, 2526 (1991)), and scanning force microscopes are used for mechanical modification of layers (V. Bouchiat and D. Esteve, Appl. Phys. Lett. 69, 3098 (1996)) or metal conductor paths (R. Rank, H. Bruckl, J. Kretz, I. Monch and G. Reiss, Vacuum 48, 467 (1997)) and for field-induced local oxidation of silicon (C. Schonenberger, N. Kramer, Microelectron. Eng. 32, 203 (1996)).
Within the group of inorganic resist materials, amorphous carbon layers hold an important place (K. Kragler, E. Gunther, R. Leuschner, G. Falk, A. Hammerschmidt, H. von Seggern and G. Saemann-lschenko, Appl. Phys. Lett. 67, 1163 (1995)). Among the advantages are that the reactivity of the amorphous carbon with most substrates is negligible, amorphous carbon is resistant to halogen plasma, so that structured carbon films are suitable as etch masks for halogen-plasma etching for structure transfer into underlying layers. Carbon films can easily be removed by means of reactive ion etching with oxygen or hydrogen.
It is known that amorphous carbon layers can be structured in that the structure of a layer lying above the carbon is transferred into the carbon by etching.
Direct structuring of amorphous carbon films by means of etching in the electron beam in a defined oxygen environment is also known. Structure sizes down to 0.5 .mu.m have been achieved by this method (D. Wang, P. C. Hoyle, J. R. A. Cleaver, G. A. Porkolab and N. C. MacDonald, J. Vac. Sci. Technol. B 13, 1984 (1995)). While the reaction products are volatile in an advantageous manner in this case, a substantial disadvantage of this method consists in that structures generated in this manner in the amorphous carbon cannot be transferred into silicon substrates lying below the carbon layer because an etch-resistant layer occurs at the silicon surface during structuring.
Local graphitization of diamond-like carbon films in the focus of a laser and production of masks through the use of the different oxygen plasma etch rates of graphite and diamond-like carbon are also known. In this way, structures with sizes in the range of 5 .mu.m could be generated (J. Seth, S. V. Babu, V. G. Ralchenko, T. V. Kononenko, V. P. Ageev and V. E. Strelnitsky, Thin Solid Films, 254, 92 (1995)).